Back pain can be caused by a variety of factors, including, but not limited to the rupture or degeneration of one or more intervertebral discs due to degenerative disk disease, spondylolisthesis, deformative disorders, trauma, tumors and the like. In such causes, pain typically results from compression or irritation of spinal nerve roots by reduced spacing between adjacent vertebrae, a damaged disk and/or misalignment of the spine resulting of the injury or degeneration.
Common forms of treating such pain include various types of surgical procedures in which a damaged disk may be partially or totally excised, and one or more implants is inserted between adjacent vertebrae in an effort to restore the natural spacing and alignment between the vertebrae that existed previous to the injury or degeneration, so as to relieve the compression, irritation or pressure on the spinal nerve or nerves and thereby eliminate or significantly reduce the pain that the patient is experiencing. Typically, the one or more implants are used together with substances to encourage bone ingrowth to facilitate fusion between the adjacent vertebrae. Some procedures provide implants that allow at least some limited motion between the adjacent vertebrae, even after opposite ends of the implant are fixed to the adjacent vertebrae, respectively.
Among know procedures for performing fusion are PLIF (posterior lumbar interbody fusion), ALIF (anterior lumbar interbody fusion) and TLIF (transverse or transforaminal lumbar interbody fusion). A PLIF procedure achieves spinal fusion in the low back by inserting an implant such as a cage and, typically, graft material (to encourage bone ingrowth) directly into the disc space between adjacent vertebrae. The surgical approach for PLIF is from the back of the patient, posterior to the spinal column.
An ALIF procedure is similar to the PLIF procedure), except that in the ALIF procedure, the disc space is fused by approaching the spine through the abdomen, from an anterior approach, instead of through the lower back, from a posterior approach. Although previously there was a lot of interest in perfecting an endoscopic approach for ALIF surgery, it has largely been abandoned because it placed the great vessels (aorta and vena cava) at too great a risk.
A TLIF procedure involves a posterior and lateral approach to the disc space. To gain access to the disc space, the facet joint may be removed whereby access is gained via the nerve foramen. The TLIF procedure leaves more of the soft tissue intact compared to the PLIF procedure and is therefore less traumatic. Unlike the PLIF procedure, the TLIF procedure requires only minimal manipulation of neural tissues, thereby reducing the risk of nerve damage resultant from the fusion procedure. Typically only a single implant is placed in a TLIF procedure. The implant is inserted from a postero-lateral approach, as noted, and is ultimately placed in the middle-to-anterior aspect of the disc space.
In the typical ALIF, PLIF and TLIF procedures described, the adjacent vertebrae must be distracted apart by a substantial amount in order to allow the surgeon to advance the implant therebetween with relatively little resistance to the advancement of the implant along its delivery path. Also, the surgeon must typically release the implant at least once (generally more than once) as the implant is being delivered along the delivery path, since the implant is generally aligned posterior to anterior relative to the vertebrae, but is rotated along the course of the delivery path so that the orientation of the implant at the ultimate (target) position of implantation in the anterior aspect of the disc space, is generally transverse to the anterior-posterior direction. Thus, delivery of the implant generally requires temporary grasping or attachment of a delivery instrument and at least one iteration of releasing the grasp or attachment, repositioning the delivery instrument relative to the implant, reattaching or re-grasping the implant and further advancing the implant. This is not only cumbersome and extends the time to complete the procedure, but also runs the risk of displacing the implant from its current orientation and desired delivery path, which would result in mal-placement of the implant and repositioning or even removal and re-insertion of the implant.
Still further, release and reattachment of an inserted to an implant is not always possible with currently existing TLIF implant/inserter designs. In such cases, the surgeon has to rely on various impactors to push and position the TLIF implant properly, and this can be difficult and therefore is sometimes not successful.
There is a continuing need for procedures that require less removal of tissues during the performance thereof. In this regard it would be desirable to provide implants and procedures that would require less removal f bone from the adjacent vertebrae than required by typical current procedures. It would further be desirable to provide implants and procedures that require less distraction of the adjacent vertebrae during placement of the implant. It would further be desirable to provide implants and instruments that do not require releasing and reattaching/re-grasping the implant during delivery of the implant. The present invention meets at least all of the above needs and desires.